Ohio quake linked to wastewater well

— -- Ohio earthquakes tied to a deep wastewater disposal well are raising safety questions, amid a nationwide natural gas drilling boom.

On New Year's Eve, a magnitude-4.0 quake outside Youngstown, Ohio, shook the ground as far north as Toronto. Quake experts tied the event, the latest and largest in a series stretching back to March, to a 1.7-mile-deep wastewater disposal well, prompting state officials to shut it down.

"Earthquakes may continue there for years," says seismologist Won-Yong Kim of the Lamont-Doherty Earth Observatory at Columbia University in New York. "For Youngstown, this was quite an unusual earthquake."

Since an incident outside Denver in the 1960s, geologists have known that deep injections of wastewater, placed there to avoid cleanup costs, can trigger earthquakes, says Art McGarr of the U.S. Geological Survey office in Menlo Park, Calif. The Ohio quake, which caused no damage, joins similar recent quakes in Texas and Arkansas linked to injections of wastewater from drilling operations.

"We support the state's action" on closing down this well, says Tom Stewart, head of the Ohio Oil and Gas Association. He notes that 177 other disposal wells dot Ohio, handling nearly 300 million gallons of wastewater yearly without incident.

"That's why we need regulation by experts," Stewart says.

Stewart and others in the industry stress that disposal wells are not the same as wells drilled for "fracking," which shatters shale layers underground with drilling fluid in order to free natural gas. Concern over disposal-well quakes comes as fracking is booming nationwide, producing more wastewater to send to such deep disposal wells. Such wells have long been used to dump wastewater from operations in pressurized oil fields and natural gas seams, which is where seismologists first learned about induced quakes.

"If we want the energy, and I think we do, we have to figure out how to handle this," says natural resources economist Michal Moore of Canada's University of Calgary. The alternative is to send such wastewater to water-treatment plants not designed to handle industrial waste, he says. "This earthquake is a cautionary tale at this point, " Moore says.

Fracking takes place in shale layers much shallower than the "basement" rock, more than 2 miles deep in Ohio, where earthquake faults are. However, fracking triggers small seismic motions, "intended to be on a scale that is acceptable," says engineering expert Anthony Ingraffea of Cornell University. What is "acceptable," remains the big question, Ingraffea adds, seeing as more quakes are likely.